8[1]Murray B H, Moore A. Sizing the Internet[ M]. A White Paper:Cyveillance, Inc. 2000.
9[2]Lawrence S, Giles L. Acxessibility and distribution of information on the Web[J]. Nature. 1999, 400:107～ 109.
10[3]Cho J, Garcia - Molina H. The evolution of the Web and implication for an incremental crawler[J]. In: Proc of the 26th International Conference on Very Large Databases ( VLDB' 00), 2000.
